<template>
  <div>
    <span class="s-canvas" @click="changeCode">
      <canvas
        ref="canvasBox"
        :width="contentWidth"
        :height="contentHeight"
      ></canvas>
    </span>
  </div>
</template>

<script>
export default {
  name: "verificationCode",
  data() {
    return {
      identifyCode: "",
    };
  },
  props: {
    type: {
      //验证码类型
      type: String,
      default: "1",
    },
    identifyCodes: {
      //验证码从该字段中抽取生成
      type: String,
      default: "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ",
    },
    fontSizeMin: {
      // 字体最小值
      type: Number,
      default: 25,
    },
    fontSizeMax: {
      // 字体最大值
      type: Number,
      default: 35,
    },
    backgroundColorMin: {
      // 验证码图片背景色最小值
      type: Number,
      default: 200,
    },
    backgroundColorMax: {
      // 验证码图片背景色最大值
      type: Number,
      default: 220,
    },
    dotColorMin: {
      // 背景干扰点最小值
      type: Number,
      default: 60,
    },
    dotColorMax: {
      // 背景干扰点最大值
      type: Number,
      default: 120,
    },
    contentWidth: {
      //容器宽度
      type: Number,
      default: 100,
    },
    contentHeight: {
      //容器高度
      type: Number,
      default: 44,
    },
  },
  watch: {
    identifyCode() {
      this.drawPic();
    },
  },
  mounted() {
    this.drawPic();
    this.changeCode();
  },
  methods: {
    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      let r = this.randomNum(min, max);
      let g = this.randomNum(min, max);
      let b = this.randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    },
    drawPic() {
      let canvas = this.$refs.canvasBox;
      let ctx = canvas.getContext("2d");
      ctx.textBaseline = "bottom";
      // 绘制背景
      ctx.fillStyle = this.randomColor(
        this.backgroundColorMin,
        this.backgroundColorMax
      );
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
      // 绘制文字
      for (let i = 0; i < this.identifyCode.length; i++) {
        this.drawText(ctx, this.identifyCode[i], i);
      }
      this.drawLine(ctx);
      this.drawDot(ctx);
    },
    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(50, 160); //随机生成字体颜色
      ctx.font =
        this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei"; //随机生成字体大小
      let x =
        (i + 1) * ((this.contentWidth - 10) / (this.identifyCode.length + 1));
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
      var deg = this.randomNum(-30, 30);
      // 修改坐标原点和旋转角度
      ctx.translate(x, y);
      if ((i != 1 && i != 3) || this.type != 2) {
        ctx.rotate((deg * Math.PI) / 180);
      }

      ctx.fillText(txt, 0, 0);
      // 恢复坐标原点和旋转角度
      if ((i != 1 && i != 3) || this.type != 2) {
        ctx.rotate((-deg * Math.PI) / 180);
      }
      ctx.translate(-x, -y);
    },
    drawLine(ctx) {
      // 绘制干扰线
      for (let i = 0; i < 4; i++) {
        ctx.strokeStyle = this.randomColor(100, 200);
        ctx.beginPath();
        ctx.moveTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        );
        ctx.lineTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        );
        ctx.stroke();
      }
    },
    drawDot(ctx) {
      // 绘制干扰点
      for (let i = 0; i < 30; i++) {
        ctx.fillStyle = this.randomColor(0, 255);
        ctx.beginPath();
        ctx.arc(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight),
          1,
          0,
          2 * Math.PI
        );
        ctx.fill();
      }
    },
    /*切换验证码start*/
    changeCode() {
      this.identifyCode = "";
      this.makeCode(this.identifyCodes, 4);
    },
    makeCode(e, n) {
      if (this.type == 1) {
        for (let i = 0; i < n; i++) {
          this.identifyCode += e[this.randomNum(0, e.length)];
        }
        this.$emit("changeCode", this.identifyCode);
      } else if (this.type == 2) {
        let num1 = e[this.randomNum(0, e.length)];
        let num2 = e[this.randomNum(0, e.length)];
        this.identifyCode += num1;
        this.identifyCode += "+";
        this.identifyCode += num2;
        this.identifyCode += "=?";
        this.$emit("changeCode", Number(num1) + Number(num2));
      } else {
        console.error("验证码类型错误");
      }
    },
  },
};
</script>
<style lang="scss" scoped>
.box {
  display: inline-block;
}
</style>
